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Merge branch 'for-next/kcsan' into for-next/core

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* for-next/kcsan:
  arm64: kcsan: Support detecting more missing memory barriers
  asm-generic: Add memory barrier dma_mb()
This commit is contained in:
Will Deacon 2022-07-25 10:56:40 +01:00
commit b7c47fd771
3 changed files with 20 additions and 11 deletions
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11
Documentation/memory-barriers.txt
View file

@ -1894,6 +1894,7 @@ There are some more advanced barrier functions:
(*) dma_wmb();
(*) dma_rmb();
(*) dma_mb();
These are for use with consistent memory to guarantee the ordering
of writes or reads of shared memory accessible to both the CPU and a
@ -1925,11 +1926,11 @@ There are some more advanced barrier functions:
The dma_rmb() allows us guarantee the device has released ownership
before we read the data from the descriptor, and the dma_wmb() allows
us to guarantee the data is written to the descriptor before the device
can see it now has ownership. Note that, when using writel(), a prior
wmb() is not needed to guarantee that the cache coherent memory writes
have completed before writing to the MMIO region. The cheaper
writel_relaxed() does not provide this guarantee and must not be used
here.
can see it now has ownership. The dma_mb() implies both a dma_rmb() and
a dma_wmb(). Note that, when using writel(), a prior wmb() is not needed
to guarantee that the cache coherent memory writes have completed before
writing to the MMIO region. The cheaper writel_relaxed() does not provide
this guarantee and must not be used here.
See the subsection "Kernel I/O barrier effects" for more information on
relaxed I/O accessors and the Documentation/core-api/dma-api.rst file for

12
arch/arm64/include/asm/barrier.h
View file

@ -50,13 +50,13 @@
#define pmr_sync() do {} while (0)
#endif
#define mb() dsb(sy)
#define rmb() dsb(ld)
#define wmb() dsb(st)
#define __mb() dsb(sy)
#define __rmb() dsb(ld)
#define __wmb() dsb(st)
#define dma_mb() dmb(osh)
#define dma_rmb() dmb(oshld)
#define dma_wmb() dmb(oshst)
#define __dma_mb() dmb(osh)
#define __dma_rmb() dmb(oshld)
#define __dma_wmb() dmb(oshst)
#define io_stop_wc() dgh()

8
include/asm-generic/barrier.h
View file

@ -38,6 +38,10 @@
#define wmb() do { kcsan_wmb(); __wmb(); } while (0)
#endif
#ifdef __dma_mb
#define dma_mb() do { kcsan_mb(); __dma_mb(); } while (0)
#endif
#ifdef __dma_rmb
#define dma_rmb() do { kcsan_rmb(); __dma_rmb(); } while (0)
#endif
@ -65,6 +69,10 @@
#define wmb() mb()
#endif
#ifndef dma_mb
#define dma_mb() mb()
#endif
#ifndef dma_rmb
#define dma_rmb() rmb()
#endif